ROGER MORTIMER, EARL OF MARCH, was a ward of Piers Gaveston, and held many important offices in the reign of Edward II, being appointed Lieutenant of Ireland in 1317.

He sided with Lancaster in his opposition to the king, was taken prisoner in 1322, and condemned to perpetual captivity. Escaping in 1324 he fled to France. In 1325 Queen Isabella being sent over to the French court, Mortimer formed an intrigue with her, and in the next year accompanied her to England. The king fled, and was subsequently deposed, and in 1327 Mortimer was master of the situation.

For nearly four years the queen and Mortimer ruled the country. All attempts to upset or curtail their power were defeated; the Earl of Lancaster, who endeavoured to rival Mortimer, was compelled to submit in 1328, and a plot set on foot by the king's uncle, Edmund, Earl of Kent, which had for its object the restoration of Edward II, who was supposed to be still alive, failed utterly, and Kent was executed (1330).

But this was Mortimer's last act, for the young king [Edward III] had determined to rid himself of the intolerable yoke he had borne so long. Mortimer was surprised in Nottingham Castle, arraigned as a traitor, accused of the death of Edward II and the Earl of Kent, and hanged, to the universal joy of the nation. His arrogance and vindictiveness recalled the worst features of the Despencers, and his adultery with the queen rendered him still more odious in the eyes of the people.

Excerpted from:

The Dictionary of English History. Sidney J. Low and F. S. Pulling, eds.
London: Cassell and Company, Ltd., 1910. 742.